Refactor router by cpuguy83 · Pull Request #987 · project-dalec/dalec

cpuguy83 · 2026-03-06T00:42:19Z

This is in preparation of #986
It also just generally fixes issues with routing for routes with sub-routers (e.g. see that targets.md now populates certain debug routes).

It moves to using a single, flat router for all routes.
Route registration happens at request time since available routes can be spec-dependent.
For the targets json API (docker build --call frontend.targets,format=json) it now includes a field to give extra hints to clients, such as the vscode extension, on if the targets are explicit in the spec or not.

Copilot

Pull request overview

This PR refactors Dalec’s frontend routing from a hierarchical, nested BuildMux to a single flat frontend.Router with fully-qualified routes. It also changes the plugin model to provide routes at request time (enabling spec-aware route availability), and extends the targets listing payload with dalec-specific metadata (specDefined, hidden) to help clients.

Changes:

Replace frontend.BuildMux with a flat frontend.Router and update dispatch/listing/subrequest handling accordingly.
Switch target plugins from “build-target” handlers to “route-provider” plugins returning []frontend.Route.
Add internal/gwutil wrappers to preserve CurrentFrontend/SpecLoader across gwclient wrappers; update docs and tooling to the new targets and routing flow.

Reviewed changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
website/docs/examples/targets.md	Updates the documented target list to include new RPM debug subroutes.
test/testenv/buildx.go	Wraps gateway client wrappers with `gwutil.WithCurrentFrontend` to preserve interfaces.
test/fixtures/phony/main.go	Migrates test fixture frontend from `BuildMux` to `Router`.
targets/windows/handler.go	Converts Windows target handling into a route provider (`Routes`) returning flat routes.
targets/register.go	Replaces build-target registration with route-provider registration.
targets/plugin/init.go	Registers distro route providers instead of build-target handlers.
targets/linux/rpm/rockylinux/common.go	Removes old `Handlers`/builtin mux target map usage.
targets/linux/rpm/distro/distro.go	Converts RPM distro config from mux-based handling to flat `Routes`, includes debug routes.
targets/linux/rpm/distro/debug.go	Replaces nested debug mux with `DebugRoutes` returning flat debug routes.
targets/linux/rpm/azlinux/common.go	Removes old `Handlers`/builtin mux target map usage.
targets/linux/rpm/almalinux/common.go	Removes old `Handlers`/builtin mux target map usage.
targets/linux/distro_handler.go	Refactors base image config resolution helper (`resolveBaseConfig`).
targets/linux/deb/ubuntu/common.go	Removes old `Handlers`/builtin mux target map usage.
targets/linux/deb/distro/distro.go	Converts DEB distro config from mux-based handling to flat `Routes`.
targets/linux/deb/debian/common.go	Removes old `Handlers`/builtin mux target map usage.
internal/plugins/types.go	Changes plugin type contract to `TypeRouteProvider` with `RouteProvider` interface.
internal/gwutil/gwutil.go	Introduces helper to preserve `CurrentFrontend` and `SpecLoader` across client wrapping.
internal/frontendapi/router.go	Replaces build-router creation with `NewRouter` that loads route providers and caches spec loads.
frontend/router_test.go	Adds tests for router dispatch (exact match, prefix match, default route, not-found).
frontend/router.go	Adds the new flat router, extended target list response, and spec-loading helper.
frontend/mux_test.go	Removes old mux tests (replaced by router tests).
frontend/mux.go	Removes the old hierarchical `BuildMux` implementation.
frontend/debug/plugin/init.go	Removes debug plugin registration via the old build-target plugin type.
frontend/debug/handler.go	Converts debug routing to flat `debug.Routes(prefix)` route definitions.
frontend/client.go	Extracts shared client/opts helpers and subrequest handlers from the removed mux.
frontend/build.go	Updates platform wrapper to preserve `CurrentFrontend` via `gwutil`.
cmd/worker-img-matrix/main.go	Updates worker matrix generation to load route providers and discover `/worker` routes.
cmd/gen-doc-targets/main.go	Updates doc target generation to use the new router and provide a stub client for empty-spec loading.
cmd/frontend/main.go	Creates the router per request and dispatches through `Router.Handler(WithTargetForwardingHandler)`.

internal/gwutil/gwutil.go

frontend/router.go

internal/frontendapi/router.go

frontend/router.go

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 3 comments.

frontend/router.go

targets/linux/deb/distro/distro.go

targets/windows/handler.go

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 5 comments.

cmd/frontend/main.go

frontend/router.go

Copilot · 2026-03-06T06:05:36Z

frontend/router.go

+				Target: bktargets.Target{
+					Name:        frontendKey,
+					Description: fmt.Sprintf("Forwarded to custom frontend: %s", frontendTarget.Frontend.Image),
+				},


The forwarding route metadata (Info) does not set SpecDefined. If the forwarded frontend came from spec.Targets (which is the only way this route is added), setting SpecDefined=true here would make the target list output more accurate, especially in the fallback path when querying the forwarded frontend fails.

Suggested change

Target: bktargets.Target{

Name: frontendKey,

Description: fmt.Sprintf("Forwarded to custom frontend: %s", frontendTarget.Frontend.Image),

},

Target: bktargets.Target{

Name: frontendKey,

Description: fmt.Sprintf("Forwarded to custom frontend: %s", frontendTarget.Frontend.Image),

},

SpecDefined: true,

cmd/worker-img-matrix/main.go

invidian

Comments for frontend: replace BuildMux with flat Router.

frontend/router_test.go

internal/frontendapi/router.go

invidian · 2026-03-06T08:42:52Z

targets/plugin/init.go

@@ -11,23 +12,49 @@ import (
 )

 func init() {


While we're at it, if we use plugins only for building routes and we already have some statically defined routes, I wonder if we could load those explicitly in internal/frontendapi/router.go or somewhere along the way in the composition tree, while I guess still keeping logic for loading from plugins from some external sources (although perhaps exposing Dalec as a library would still be better so wrappers can do their own transparent composition?)

That might be out of scope of course.

frontend/mux.go

frontend/router.go

invidian

For frontend: make route registration spec-aware

targets/windows/handler.go

internal/frontendapi/router.go

internal/gwutil/gwutil.go

Move standalone types, constants, and functions from mux.go into a dedicated client.go file. This is a pure code movement with no behavioral changes, separating client/request helpers from the BuildMux routing logic to prepare for replacing BuildMux with a flat Router. Signed-off-by: Brian Goff <cpuguy83@gmail.com>

Replace the hierarchical BuildMux (nested sub-muxes) with a single flat Router that uses fully-qualified route paths like "azlinux3/container" and "debug/resolve". All routes are registered at startup via RouteProvider plugins instead of being lazily discovered through handler invocation. Key changes: - New Router type in frontend/router.go with exact and longest-prefix match dispatch - New RouteProvider plugin interface replaces BuildHandler/BuildTarget - Distro packages export Routes(prefix) instead of Handle() methods - Target list API returns SpecDefined annotation without invoking handlers - Remove all dead BuildMux code, unused Handlers() funcs, and the debug/plugin/init.go registration shim Signed-off-by: Brian Goff <cpuguy83@gmail.com>

Load the spec once in NewRouter via LoadSpecForRouting and pass the *dalec.Spec to each RouteProvider.Routes() call. This enables: - SpecDefined annotation on each route (whether the target key appears in spec.Targets), used by the target list API - Per-request NewRouter(ctx, client) in the BuildFunc, since route registration now needs the gateway client - LoadSpecForRouting() helper in frontend/router.go that performs lenient arg substitution for routing purposes only - Each distro registers as a separate RouteProvider via RegisterRouteProvider() - Bare distro prefix routes (e.g. "mariner2") as hidden aliases for the default container handler - Hidden field on frontend.Target to exclude alias routes from the target list while keeping them dispatchable - DebugRoutes now registers individual sub-routes (buildroot, sources, spec) instead of a single prefix handler - gen-doc-targets uses a stub gwclient.Client to set up routes for documentation generation Signed-off-by: Brian Goff <cpuguy83@gmail.com>

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

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cpuguy83 force-pushed the refactor_router branch from 6aec426 to 6417397 Compare March 6, 2026 05:57

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cpuguy83 self-assigned this Mar 9, 2026

cpuguy83 force-pushed the refactor_router branch from 6417397 to 11b3e2c Compare March 12, 2026 22:56

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cpuguy83 added 3 commits March 13, 2026 09:27

frontend: fix gwclient.Client wrappers losing CurrentFrontend interface

1e4d420

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

cpuguy83 force-pushed the refactor_router branch from 11b3e2c to 1e4d420 Compare March 13, 2026 16:29

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